Download Dynamic smile visualization and quantification: Part 2

ORIGINAL ARTICLE
Dynamic smile visualization and quantification:
Part 2. Smile analysis and treatment strategies
David M. Sarver, DMD, MS,a and Marc B. Ackerman, DMDb
Vestavia Hills, Ala, and Bryn Mawr, Pa
The “art of the smile” lies in the clinician’s ability to recognize the positive elements of beauty in each patient
and then create a strategy to enhance the attributes that fall outside the parameters of the prevailing esthetic
concept. New technologies have enhanced our ability to see our patients more dynamically and facilitated
the quantification and communication of newer concepts of function and appearance. In a 2-part article, we
present a comprehensive methodology for recording, assessing, and planning treatment of the smile in 4
dimensions. In part 1, we discussed the evolution of smile analysis and reviewed the dynamic records
needed. In part 2, we review smile analysis and treatment strategies and present a brief case report. (Am J
Orthod Dentofacial Orthop 2003;124:116-27)
S
mile analysis is traditionally performed in 1
view—the frontal view.1-9 But just as a person’s
overall appearance is 3-dimensional (we see
people frontally only a fraction of the time), so then
should be the treatment of the smile. We have expanded
smile analysis to include 3 other dimensions— oblique,
sagittal, and over time— each having an important role
in smile composition.
It is important to differentiate between the social
smile and the enjoyment smile. The social smile is a
voluntary smile a person uses in social settings or when
posing for a photograph. When you are introduced to
someone, your smile indicates that you are friendly and
“pleased to meet” that person. The enjoyment smile1,10
is an involuntary smile and represents the emotion you
are experiencing at that moment. The enjoyment smile
therefore has many descriptors, such as laughing, wry,
knowing, or insipid. The differing visual presentations
reflect inner emotions and are mechanically governed
by all the facial muscles of expression and the differential nuances of recruitment and use of these muscle
sets. For example, in the knowing smile, the corners of
the mouth are elevated slightly, and the eyebrows might
also be raised. We call this a smile, but indeed the lips
may not even be parted to expose the teeth. According
a
Adjunct professor, Department of Orthodontics, University of North Carolina,
Chapel Hill, USA; and private practice, Vestavia Hills, Ala.
b
Clinical associate, Department of Orthodontics, University of Pennsylvania
School of Dental Medicine, Philadelphia, USA; director of orthodontics,
Division of Dentistry, Children’s Hospital of Philadelphia, USA; and private
practice, Bryn Mawr, Pa.
Reprint requests to: David M. Sarver, DMD, MS, 1705 Vestavia Parkway,
Vestavia Hills, AL 35216; e-mail, [email protected].
Submitted, August 2002; revised and accepted, December 2002.
Copyright © 2003 by the American Association of Orthodontists.
0889-5406/2003/$30.00 ⫹ 0
doi:10.1016/S0889-5406(03)00307-X
116
to both Darwin and Duchenne,10,11 we “smile with our
eyes.”
When treating occlusal discrepancies, the orthodontist must have a repeatable position of tooth and jaw
relationships to use as a reference point. In dentistry,
the most accepted reference position in occlusion is the
mandible placed in its most retruded contact position.
In treating the smile, the social smile generally represents a repeatable smile.1,12 However, a social smile
can mature and might not be consistent over time in
some patients.
We have chosen the social smile as the representation from which we will analyze the smile in 4
dimensions: frontal, oblique, sagittal, and time-specific
(Fig 1).
FRONTAL DIMENSION
To visualize and quantify the frontal smile, Ackerman and Ackerman1,13 developed a ratio, called the
smile index, that describes the area framed by the
vermilion borders of the lips during the social smile.
The smile index is determined by dividing the intercommissure width by the interlabial gap during smile
(Fig 2). This ratio is helpful for comparing smiles
among different patients or across time in 1 patient.
Frontally, we can visualize and quantify 2 major
dimensions of the smile: vertical and transverse characteristics. The vertical characteristics of the smile are
broadly categorized into 2 main features: those pertaining to incisor display and those pertaining to gingival
display. The clinician must first ascertain whether the
patient displays adequate gingival and dental architecture in the smile frame. If, for example, the patient
shows less than 75% of the central incisor crowns at
smile, tooth display is considered inadequate.6 The
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Sarver and Ackerman 117
Fig 1. Three spatial views of systematic smile evaluation: frontal, oblique, and profile. Fourth
dimension—maturation and aging—is critical in short- and long-term goal setting for treatment,
retention, and maintenance.
Fig 2. Smile index calculated by measuring intercommissure width and dividing by interlabial gap during
smile. This patient has small smile index value with
substantial incisor display on smile.
question then arises, what elements of the system are
contributory? In this example, inadequate incisor display can be due to a combination of vertical maxillary
deficiency, limited smile area (a large smile index), and
short clinical crown height. If short clinical crown
height is the primary contributor to the inadequate tooth
display, we must then differentiate between a lack of
tooth eruption (treated with observation), gingival encroachment (treated with cosmetic periodontics), and
short incisors secondary to attrition (treated with cosmetic dentistry).
Other vertical smile characteristics are the relation-
ships between the incisal edges of the maxillary incisors and the lower lip, and between the gingival
margins of the maxillary incisors and the upper lip. The
gingival margins of the canines should be coincident
with the upper lip and the lateral incisors positioned
slightly inferior to the adjacent teeth. It is generally
accepted that the gingival margins should be coincident
with the upper lip in the social smile. However, this is
very much a function of age, because children show
more tooth at rest and have more gingival display on
smile than do adults.
The 3 transverse characteristics of the smile in the
frontal dimension are arch form, buccal corridor,3,14,15
and the transverse cant of the maxillary occlusal plane.
Arch form plays a pivotal role in the transverse dimension of the smile. Recently, much attention has been
focused on the use of broad, square arch forms in
orthodontic treatment. When the arch form is narrow or
collapsed, the smile may also appear narrow and
therefore present inadequate transverse smile characteristics. An important consideration in widening a narrow
arch form, particularly in adults, is the axial inclination
of the buccal segments. Patients whose posterior teeth
are already flared laterally are not good candidates for
dental expansion. Patients with upright premolars and
molars have more capacity for transverse expansion;
this is true in adolescents, but it is particularly impor-
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American Journal of Orthodontics and Dentofacial Orthopedics
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Fig 3. A, When arch form is narrow, transverse smile dimension might be affected because of
insufficient transverse projection of both maxillary and mandibular arches, resulting in excessive
buccal corridors. B, Orthodontic expansion and widening dramatically improved appearance of
smile by decreasing size of buccal corridors and improving transverse smile dimension and smile
presentation.
tant in adults because sutural expansion is less likely.
Orthodontic expansion and widening of a collapsed
arch form can dramatically improve the smile by
decreasing the size of the buccal corridors and improving the transverse smile dimension (Fig 3). The transverse smile dimension (and the buccal corridor) is
related to the lateral projection of the premolars and the
molars into the buccal corridors. The wider the arch
form in the premolar area, the greater the portion of the
buccal corridor that is filled.
Arch expansion might fill out the transverse dimension of the smile, but 2 undesirable side effects could
result, and careful observation is needed to avoid these,
if possible. First, the buccal corridor can be obliterated,
resulting in a denture-like smile. Second, when the
anterior sweep of the maxillary arch is broadened (Fig
4, A), the smile arc may be flattened (Fig 4 B, C). This
is particularly important today because of the trend
toward broader arch forms. Although it may not be
possible to avoid these undesirable aspects of expansion, the clinician must make a judgment in concert
with the patient as to what tradeoffs are acceptable in
the pursuit of the ideal smile.
The term buccal corridor was initially added to
dental terminology by removable prosthodontics in the
late 1950s.14 When setting denture teeth, they sought to
recreate a natural dental presentation transversely. A
molar-to-molar smile was considered a characteristic of
a poorly constructed denture. The buccal corridor is
measured from the mesial line angle of the maxillary
first premolars to the interior portion of the commissure
of the lips. It is often represented by a ratio of the
intercommissure width divided by the distance from
first premolar to first premolar. As mentioned previously, the dimension of the buccal corridor is closely
related to arch form and will be discussed later in
relation to the sagittal position of the maxilla.
In adolescents, it is often desirable to increase arch
width with rapid maxillary expansion to create space
for nonextraction treatment. Figure 5, A shows a patient
in whom the maxillary canines are blocked out and
have insufficient room to erupt. On smile, she has
moderately excessive negative space. In the overall
treatment goal setting, expansion was required to create
enough room for the canines. The final transverse smile
dimension at age 14 years was significantly broader
(Fig 5, B), and, depending on your taste, this much
expansion might be considered excessive. However,
with further maturation (don’t forget the fourth dimension, time), the transverse smile characteristics fit
nicely in her face, and her goal of a modeling career
was not precluded (Fig 5, C).
The final transverse characteristic of the smile is the
transverse cant of the maxillary occlusal plane. Transverse cant can be due to differential eruption and
placement of the anterior teeth or skeletal asymmetry of
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Fig 4. A, When anterior sweep of maxillary arch is broadened, smile arc may flatten. Trend for
broader arch forms means clinician should beware of propensity for arch expansion to flatten smile
arc and compensate with bracket placement, or at least consider esthetic tradeoffs in all smile
dimensions. B, Patient with both dental crowding and inadequate transverse smile dimension. C,
After arch expansion, buccal corridor was significantly diminished but smile arc had flattened.
Fig 5. A, Maxillary canines were blocked out with insufficient room to erupt. Rapid palatal
expansion was recommended to increase maxillary arch length and avoid extractions. On smile,
patient had moderately excessive negative space on smile and excellent incisor display and smile
arc. B, Final transverse smile dimension at age 14 years was significantly broader, perhaps
excessive. C, But with further maturation, transverse smile characteristics fit nicely in face.
the mandible resulting in a compensatory cant of the
maxilla. Intraoral images, even mounted dental casts,
do not adequately reflect the relationship of the maxilla
to the smile. Only frontal smile visualization permits
the orthodontist to visualize any tooth-related or skeletal asymmetry transversely. The frontal smile photo-
120 Sarver and Ackerman
Fig 6. Oblique view allows clinician to see many smile
characteristics not visible frontally. Patient has 50%
maxillary incisor show on smile, and flatness of maxillary occlusal plane relative to lower lip curvature is
apparent.
American Journal of Orthodontics and Dentofacial Orthopedics
August 2003
Fig 7. Oblique view expands definition of smile arc,
from canine tip and maxillary incisor to lower lip curvature on smile, to now include molars and premolars.
This smile arc is consonant with lower lip from molar to
incisors.
Fig 8. A, In patients with sagittal skeletal discrepancies (in this case, Class III maxillary insufficiency), the frontal smile can appear esthetic. B, Oblique view reveals underlying skeletal pattern and
dental compensation.
graph, either full face or close-up, is a much better
indicator of transverse dental asymmetry than the
frontal retractor view. With good visualization and
documentation of tooth-lip relationships, the orthodontist can make appropriate adaptations in appliance
placement or make a decision as to the need for
differential growth or dental eruption modification of
the maxilla in the adolescent or surgical correction in
the adult.
Smile asymmetry may also be due to soft tissue
considerations, such as an asymmetric smile curtain. In
the asymmetric smile curtain, there is a differential
elevation of the upper lip during smile, which gives the
illusion of a transverse cant to the maxilla. This smile
characteristic emphasizes the importance of direct clinical examination in treatment planning, because this
soft tissue animation is not visible in a frontal radiograph or reflected in study models. It is poorly documented in static photographic images and is documented best in digital video clips.
OBLIQUE DIMENSION
The oblique view of the smile shows characteristics
of the smile not obtainable on the frontal view and
certainly not obtainable through any cephalometric
analysis. The palatal plane can be canted anteroposteriorly in a number of orientations. In the most desirable
orientation, the occlusal plane is consonant with the
Sarver and Ackerman 121
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Fig 9. A, Patient with Class III malocclusion secondary to maxillary deficiency. Some aspects of
vertical maxillary deficiency are present, including 50% of maxillary incisor show on smile.
Transverse smile dimension characterized by excessive buccal corridors. B, Maxillary downgraft
resulted in increased vertical incisor display. Maxillary advancement improved buccal corridor on
smile.
curvature of the lower lip on smile (smile arc, to be
discussed next). Deviations from this orientation include a downward cant of the posterior maxilla, upward
cant of the anterior maxilla, or variations of both.16 In
the initial examination and diagnostic phase of treatment, it is important to visualize the occlusal plane in
its relationship to the lower lip. Figure 6 illustrates an
open bite in preparation for maxillary surgery to close
an anterior open bite. Whether the posterior maxilla
should be impacted or the anterior maxilla should come
down depends on the amount of incisor show at rest and
on smile and the smile arc relationship, and this is best
visualized in the oblique view.
The smile arc is defined as the relationship of the
curvature of the incisal edges of the maxillary incisors,
canines, premolars, and molars to the curvature of the
lower lip in the posed social smile.1,17 In the ideal smile
arc, the curvature of the maxillary incisal edge is
parallel to the curvature of the lower lip upon smile;
consonant is used to describe this parallel relationship.
A nonconsonant or flat smile arc is characterized by a
flatter maxillary incisal curvature than the curvature of
the lower lip on smile. Early definitions of the smile arc
were limited to the curvature of the canines and the
incisors to the lower lip on smile, because smile
evaluation was made on direct frontal view. The visualization of the complete smile arc afforded by the
oblique view expands the definition of the smile arc to
include the molars and the premolars, as can be seen in
Figure 7.
SAGITTAL DIMENSION
The 2 characteristics of the smile that are best
visualized in the sagittal dimension are overjet and
incisor angulation. Excessive positive overjet is one of
the dental traits most recognizable to the lay person.
Unflattering terms, such as “Andy Gump” and “Bucky
Beaver,” have been attached to children unfortunate
enough to have inherited this dentoskeletal pattern.
How overjet is corrected orthodontically involves macro-elements, such as jaw patterns, and soft tissue
elements, such as nasal projection. In terms of the
smile, excessive positive overjet is not as readily
perceived in the frontal dimension as it is in the sagittal
dimension. For example, in many Class II patterns, the
smile is esthetic frontally, but the problem is obvious
when observed from the side. In Class III patterns, the
same may be true: the frontal smile looks esthetic (Fig
8, A), but the oblique or sagittal view shows the
underlying skeletal pattern and dental compensation
(Fig 8, B). The patient and the parents must decide with
the clinician whether this is an acceptable outcome in
terms of total appearance and oblique smile characteristics.
The amount of anterior maxillary projection also
greatly influences smile characteristics in the frontal
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American Journal of Orthodontics and Dentofacial Orthopedics
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Fig 10. A, Proclination of maxillary incisors can affect incisor display at rest and on smile. Flared
maxillary incisors tend to reduce incisor display, and upright maxillary incisors tend to increase
incisor display. Sagittal views show B, flare of maxillary incisors and, C, increased incisor display
after incisors have been uprighted.
view, even in terms of transverse smile dimension.
When the maxilla is retrusive, the wider portion of the
dental arch is positioned more posteriorly relative to the
anterior oral commissure. This creates the illusion of
greater buccal corridor in the frontal dimension. The
patient in Figure 9, A, had a Class III malocclusion due
to maxillary deficiency, both vertically (characterized
by only 50% of maxillary incisor show on smile) and
anteroposteriorly (as evidenced by the flatness of the
profile). After orthodontic decompensation, the surgical
plan was designed to advance the maxilla, rotating it
clockwise to increase the amount of incisor show at rest
and on smile. This occlusal plane rotation not only
improves the incisal display but also increases midfacial projection and diminishes mandibular projection.
The smile was greatly enhanced by the increased
vertical anterior tooth display (Fig 9, B), but the
transverse smile dimension was also greatly improved.
How was the negative space on smile reduced when
there was no maxillary expansion? The answer lies in
the 3-dimensional effect of the maxillary advancement.
As the maxilla came forward into the buccal corridor,
the negative space was reduced by the wider portion of
the maxilla coming forward into the static intercommissure width. The advancement of the maxilla results
in a wider portion of the maxilla being placed into the
buccal corridor, reducing “negative space.” Transverse
smile dimension, therefore, is a function of both arch
width and anteroposterior position of the maxillary and
mandibular arches. In other words, bringing the wider
portion of the maxilla forward simply fills up the
negative space.
Incisor proclination (placed here in the sagittal
dimension) can also have a dramatic effect on incisor
display. In simple terms, flared maxillary incisors tend
to reduce incisor display, and upright maxillary incisors
tend to increase it (Fig 10, A). A good example is the
patient in Figure 10, B. This patient had an anterior
open bite secondary to extreme anterior proclination of
the maxillary and mandibular incisors. The sagittal
view of the smile shows the flare of the maxillary
incisors; this resulted in diminished incisor show from
both the sagittal and the frontal views. The treatment
plan consisted of extracting the first premolars and
retracting the incisors. Care was taken to retract the
incisors on round wire so that the crowns rotated
around the bracket slot into a more inferior position.
This movement closed the anterior open bite and
increased incisor display as the teeth were retracted.
The profile view of the smile demonstrates the im-
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Sarver and Ackerman 123
Fig 11. A, Patient with crowding of maxillary arch and partially blocked-out canines. Smile
characterized by excessive gingival display. Alignment of posterior teeth and incisors consonant
with lower lip on smile—smile arc. Incisor crown height was 8 mm. B, C, Computer simulation of
treatment plan, keeping incisal edges in place and moving gingival margins superiorly. Orthodontic
intrusion of incisors to reduce gingival display would result in flattening of smile arc.
proved angulation and vertical position of the maxillary
incisors (Fig 10, C).
THE FOURTH DIMENSION: TIME
The growth, maturation, and aging of the perioral
soft tissues have a profound effect on the appearance of
both the resting and smiling presentations. Orthodontic
patients can be categorized as preadolescent, adolescent, and adult. In preadolescent patients, the facial soft
tissues are still in a growth phase, and treatment
decisions pertaining to the relative facial divergence
(posteriorly or anteriorly) at profile and frontal facial
soft tissue topography must take this into account.
Adolescent patients, or those at the point of pubertal
onset, have experienced the maximum velocity in the
growth of the skeletal subunits and have roughly
achieved their facial soft tissue “look.” In adults,
nuances in the aging of perioral and facial soft tissues
become increasingly important. We know from orthodontic cephalometric research that, on average, profiles flatten over time. Whether this is mostly related to
ptosis of the soft tissues or resorptive fields in the hard
tissues of the midface is still debated, but it is nevertheless a consequence of getting older.
In a direct measurement study of more than 3500
subjects, Dickens et al18 studied the changes in phil-
trum height and commissure height in patients from age
6 years to their 40s and the relationship to the smile.
These data demonstrate the lengthening of the philtrum
and commissure, with the rate of philtrum lengthening
greater than that of the commissures. This would
explain the flattening of the “M” characteristics of the
vermilion border of the upper lip in the youthful lip.
Lengthening of the philtrum and the commissure with
age is reflected in the curves demonstrating reduced
tooth display at rest and gingival display.
The effects of maturation and aging on the soft
tissues can be summarized as (1) lengthening of the
resting philtrum and commissure heights, (2) decrease
in turgor (or tissue “fleshiness”), (3) decrease in incisor
display at rest, (4) decrease in incisor display during
smile, and (5) decrease in gingival display during smile.
PROBLEM-ORIENTED TREATMENT PLANNING
AND IDENTIFYING POSITIVE ATTRIBUTES
In problem-oriented treatment planning, we identify
the problems that require improvement or correction
and focus primarily on correcting those problems. We
propose that the next fundamental component in treatment planning in the contemporary orthodontic analysis should include identifying and quantifying the
positive aspects of the patient’s esthetic arrangement.
124 Sarver and Ackerman
American Journal of Orthodontics and Dentofacial Orthopedics
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In this approach to problem-oriented treatment planning, we clearly want to fix what is wrong, but not at
the expense of what is right about an patient’s esthetic
presentation.
The following example will illustrate this principle. The patient in Figure 11, A, had crowding of the
maxillary arch with partially blocked-out canines.
Her smile is characterized by excessive gingival
display that was judged to be an esthetic problem. In
our systematic evaluation, the etiology of the gummy
smile was due primarily to the short clinical crown
height of 8 mm. Thus, our main problems (as related
to the smile) were short incisor heights and excessive
gingival display on smile. That is the problem list,
but what is right about the smile? What attributes of
this smile do we want to preserve? Her maxillary
occlusal arc is consonant with the lower lip curvature
on smile; thus her smile arc is ideal. One option to
reduce the gumminess of the smile is intrusion of the
maxillary incisors, but this would result in an undesirable flattening of her smile arc. When we visualized her smile with computer imaging and simulated
cosmetic periodontal crown lengthening (Fig 11, B),
the treatment plan became clear. Computer imaging
helps the clinician to see the plan and cogently
present treatment options to the patient and family,
as well as to communicate with other professionals
involved in the care of the patient. The subsequent
treatment strategy is (1) maintain the incisal edges in
their current vertical position, (2) extrude the maxillary canines to level the arch, and (3) finish with
periodontal crown lengthening. Bracket placement
was critical to our orthodontic approach because we
wanted to level the anterior and posterior segments in
a continuous archwire, bypassing the canines. In this
way, we protect the smile arc, identified in our
original examination and diagnosis as a good feature
to be maintained. When a full-dimension wire was
reached, a light auxiliary thermoelastic wire was
threaded from the auxiliary tube on the maxillary
molars and ligated to the anterior archwire, so that
the canines could be extruded without a subsequent
intrusion of the maxillary incisors.
One of the most accepted attributes of an esthetically pleasing smile is the smile arc. The anatomic
contributions to the smile arc are visualized best in the
oblique dimension, but the factors influencing it are
found in all 3 dimensions. When attempting to alter the
smile arc, the following strategies can be used:
directed headgear, vertical control functional appliances, and the Herbst appliance.
In late adolescent and adult patients, surgical modification of the maxillary occlusal plane is often
indicated. Maxillary advancement coupled with
clockwise occlusal plane rotation will harmonize the
positions of the maxillary incisal edges with the
lower lip and improve the buccal corridors by
bringing the wider portion of the maxillary arch
forward.
Bracket placement is also crucial to either maintaining or modifying the smile arc. Conventional
straight-wire prescriptions call for a 0.5-mm difference in the incisal-edge-to-bracket-slot distance between maxillary central and lateral incisors. It has
been our experience that a distance of 1 to 1.5 mm
between lateral and central incisor bracket slots and
the incisal edges is needed to preserve or create
consonant smile arcs. This helps to superiorly position the lateral incisors and preserve the gradual
sweep of the smile arc.
Cosmetic porcelain laminates or composite bonding
can also play a role in enhancing the smile arc.
Orthodontic treatment planning must consider tooth
morphology, and multidisciplinary care might be
indicated. Figure 12, A, demonstrates how the
oblique smile close-up helps the orthodontist to
visualize where to place the teeth as the gingival
margins relate to the upper lip on smile and as the
position of the incisal edges relates to the lower lip
on smile, so that the porcelain laminates create a
harmonious relationship on smile (Fig 12, B).
Finally, enamel odontoplasty can be used to conservatively reshape the incisal edges of the maxillary
anterior teeth during orthodontic finishing.
1. Treating the occlusal plane in preadolescents with a
growth modification appliance can be advantageous.
Examples of these appliances include vertically
2.
3.
4.
5.
CASE ILLUSTRATION
This 45-year-old man was referred by his dentist
after he had finally exfoliated his maxillary right
deciduous canine (Fig 13, A). The dentist was evaluating him for restoration of the missing tooth but, because
of the malocclusion, referred him for a preprosthodontic orthodontic consultation. He had Class I posterior
relationships but also an edge-to-edge incisal relationship that had resulted in attrition of both the maxillary
and mandibular anterior teeth. His overall dental condition reflected a remarkable amount of attrition and
wear.
Our systematic evaluation yielded the following
information.
Resting tooth-lip relationships included a philtrum
height of 28 mm, commissure height of 30 mm, and
maxillary incisor display at rest of 1 mm. Dynamic
American Journal of Orthodontics and Dentofacial Orthopedics
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Sarver and Ackerman 125
Fig 12. A, Close-up image of oblique smile helps clinician visualize placement of teeth as gingival
margins relate to upper lip on smile and as incisal edges relate to lower lip on smile. B, Coordinating
smile arc goals, specific bracket placement, and final laminates result in outstanding smile.
Fig 13. Maxillary right lateral incisor was congenitally missing, and retained maxillary right
deciduous canine had just been lost. Maxillary right canine was in lateral incisor position. Note
severe attrition of maxillary anterior teeth and variable gingival heights relative to each other and the
upper lip on smile. Despite attrition, smile arc was consonant, with cusp tips and incisal edges
parallel to lower lip. B, Significant intrusion of mandibular incisors needed to provide vertical
clearance for restoration and enough room for ideal smile arc after restoration of maxillary incisors.
C, Bracket placement and differential intrusion of maxillary incisors resulted in coordination of
gingival margins with upper lip on smile, and coordination to each other. D, After final full coverage
restoration of maxillary and mandibular dentitions. E, Targets of dynamic smile were attained,
including alignment of maxillary incisor gingival margins with upper lip on smile and incisal edges,
canine tips, and premolar tips in a consonant relationship to lower lip on smile. F, Oblique view
shows successful alignment of smile arc and result of sufficient mandibular incisor intrusion to reach
treatment goals.
tooth-lip relationships (vertical dimensions of the
smile) included 100% maxillary anterior tooth display,
no excessive gingival display on smile, and varied
crown heights due to the attrition. The maxillary right
lateral incisor was congenitally missing, and the permanent canine had drifted anteriorly to fill the lateral
position. The right deciduous canine, which had re-
cently exfoliated, had filled in the canine space. The
crowns were measured individually so that we could
plan vertical position of the gingival margins appropriately. The right canine was 8 mm, the right central
incisor was 7 mm, the left central incisor was 6.5 mm,
and the left lateral incisor was ⫺7 mm.
Frontally, no transverse cant of the maxilla was
126 Sarver and Ackerman
noted, although some slight asymmetry of the smile
appeared secondary to the varied anterior tooth heights.
Transverse smile dimension as it related to the buccal
corridors was judged to be quite good.
No anteroposterior cant was noted in the oblique
and sagittal views, and the smile arc was consonant.
Although the anterior teeth were quite short, they were,
with the premolars and canines, parallel to the curvature of the lower lip on smile.
Finally, we assessed the characteristics of the patient’s smile over time—the fourth dimension. We
calculated that the patient had experienced 40% attrition of his maxillary central incisors and 50% attrition
of the mandibular incisors. This resulted in no incisor
show at rest and diminished incisor show in speech.
Gradual diminishment of incisor display is a primary
characteristic of dental aging. Because of the patient’s
lack of overjet, the functional goals of treatment were
to orthodontically advance the maxillary incisors so
that incisor crown length could be added. As a secondary goal, we thought it was necessary to intrude the
incisors to open the bite so that restoring the lost incisor
length would not deepen the bite.
Goals of treatment
Coordinating the maxillary incisor gingival margins
with the upper lip on smile was a goal of treatment.
Many orthodontists still use arbitrary standards for
bracket placement; these might be adequate but do not
take into account the relationship of the anterior teeth to
the animated characteristics of the smile. These include
instrument-guided placement of central incisor brackets
4 mm above the incisal edge of the central incisors, 3.5
mm above the cusp tips of the lateral incisors, and 4.5
mm above the tips of the canines and in the center third
of the tooth vertically and horizontally, per straightwire prescription.
This patient presented a different challenge in
placing the bracket and its slot, because the goal was
not to align the incisal edges but to align the gingival
margins. This includes aligning the gingival margins to
each other in terms of canine, lateral, and central incisor
heights, and the gingival margins to the upper lip on
smile. Because the goal was to idealize the gingival
margins by differential intrusion or extrusion relative to
each other and the lip, the brackets were placed with the
main frame of reference being the distance of the slot
from the gingival margin, not the incisal edges. Intruding the mandibular incisors would open the bite. This
was required to provide room for vertical restoration of
both the maxillary and mandibular incisors, so significant intrusion was indicated. How much intrusion
would be required? The parameters for how much
American Journal of Orthodontics and Dentofacial Orthopedics
August 2003
interincisor distance was needed included (1) how long
the maxillary incisors needed to be to the attain desired
length, (2) how much length was needed to improve
maxillary incisor display at rest, (3) how much length
was needed to facilitate mandibular incisor restoration,
and (4) how much length was needed in the maxillary
incisors to attain the desired smile arc relationship.
Finally, the dentition would be restored, including
replacement of the missing tooth.
Evaluation of the smile and synchronization of all
the parameters of smile analysis
Figure 13, A, shows a close-up of the smiling
relationship. The gingival margins of the maxillary
incisors reasonably approximated the curvature of the
upper lip on smile, but the gingival margins were not in
the ideal esthetic position relative to the upper lip or
each other. Specifically, the maxillary right canine was
longer than the central incisor, and the lateral margin
was equal to the central gingival height. The curvature
of the premolars and anterior teeth closely approximated the curvature of the lower lip on smile (smile
arc), but the teeth were much shorter, and the curvature
of the maxillary incisors fell short of the curvature of
the lower lip.
The overall idea was, of course, to restore the
dentition, but the edge-to-edge incisal relationship was
a problem, and adding crown length would tend to
create an impinging deep bite. The interdisciplinary
plan was as follows:
Maxillary bracket positioning. In most bracket
placement schemes, the frame of reference is either the
center of the tooth (in most straight-wire schemes) or a
uniform distance from the incisal edge. In this case,
however, we were not treating a normal tooth-gingivalip relationship. Our frame of reference for maxillary
bracket placement was not the incisal edges, but the
gingival margins. It was also necessary to place the
brackets so that the gingival heights of the central
incisors were slightly higher than the lateral incisors,
and the canines slightly higher than the central incisors.
Mandibular bracket positioning. The mandibular
incisor brackets were placed as incisally as possible.
Because of the attrition, limited tooth structure was
available for bonding, but the bracket ended up in the
center of the tooth.
Bioprogressive utility arches. Maxillary and mandibular bioprogressive-type utility arches were placed,
resulting in intrusion of the mandibular incisors approximately 6 mm (Fig 13, B). Careful placement of the
maxillary brackets, related to the gingival margins
rather than the incisal edges, resulted in good alignment
of the gingival margins to the upper lip on smile (Fig
Sarver and Ackerman 127
American Journal of Orthodontics and Dentofacial Orthopedics
Volume 124, Number 2
13, C). Typically at this point, the dentist takes a
facebow mounting and performs a diagnostic wax-up to
determine whether the teeth are in the correct position
for restoration. Sometimes, we even recommend the
fabrication of a processed temporary overlay for the
patient to place over the incisors so that the patient can
see and approve the resting and smiling incisor relationships. Some space was created between the incisors
so that the crowns could be fabricated with proper
emergence profiles. As the incisors were worn vertically, they drifted together, and the contact point moved
more apically. Without recreating space, the restoration
of the incisors would have to be narrower than ideal,
with inappropriately long connectors. The final restorative outcome is shown in Figure 13, D. An important
feature of this case was the adequate intrusion of the
mandibular incisors to permit adequate incisor display
at rest and on smile. The close-up of the smile (Fig 13,
E) illustrates placement of the gingival margins to the
upper lip on smile, and the oblique close-up smile also
demonstrates the excellent smile arc characteristics (Fig
13, F).
CONCLUSIONS
In this 2-part article, we have discussed a comprehensive methodology for recording, assessing, and
planning treatment of the smile in 4 dimensions. Orthodontic history, beginning with Angle and Wuerpel, has
taught us that the “art of the smile” lies in the
clinician’s ability to recognize the positive elements of
beauty in each patient and then create a strategy to
enhance the attributes that fall outside the parameters of
the prevailing esthetic concept. The difference between
contemporary orthodontic practice and that of our
predecessors is that we now can dynamically visualize
and quantify our patients’ smiles. Orthodontic diagnosis has, in a certain sense, come full circle. But the
focus on the lineaments of the smile is not a step back
in time; rather, it represents a reemphasis of the
importance of physical diagnosis and the appreciation
of the soft tissues that both drive our treatment planning
and limit the treatment response. New technology
simply enhances our ability to see our patients more
dynamically and facilitates the quantification and communication of newer concepts of function and appearance.
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